esp32/modmachine: Fix machine.reset_cause to use IDF's esp_reset_reason.
esp32/modmachine: Fix machine.reset_cause to use IDF's esp_reset_reason.

The code previously called rtc_get_reset_reason which is a "raw" reset
cause.  The ESP-IDF massages that for the proper reset cause available from
esp_reset_reason.

Fixes issue #5134.

pfalcon/micropython,pfalcon/micropython,pfalcon/micropython,pfalcon/micropython,pfalcon/micropython